basic compatibility with SD polyfill.

src/HTMLImports.js

@@ -72,25 +72,29 @@ if (!useNative) {
       // see https://code.google.com/p/chromium/issues/detail?id=249381.
       elt.__resource = resource;
       if (isDocumentLink(elt)) {
-        var doc = importer.documents[url];
+        var doc = this.documents[url];
         // if we've never seen a document at this url
         if (!doc) {
           // generate an HTMLDocument from data
           doc = makeDocument(resource, url);
           doc.__importLink = elt;
           // TODO(sorvell): we cannot use MO to detect parsed nodes because
           // SD polyfill does not report these as mutations.
-          importer.loadSubtree(doc);
-          importer.observe(doc);
+          this.bootDocument(doc);
           // cache document
-          importer.documents[url] = doc;
+          this.documents[url] = doc;
         }
         // don't store import record until we're actually loaded
         // store document resource
         elt.import = doc;
       }
       parser.parseNext();
     },
+    bootDocument: function(doc) {
+      this.loadSubtree(doc);
+      this.observe(doc);
+      parser.parseNext();
+    },
     loadedAll: function() {
       parser.parseNext();
     }
@@ -152,16 +156,13 @@ if (!useNative) {
   var importer = {};
 }
 
-var wrappedDoc = window.ShadowDOMPolyfill ? wrap(document) : document;
-
-
 // NOTE: We cannot polyfill document.currentScript because it's not possible
 // both to override and maintain the ability to capture the native value;
 // therefore we choose to expose _currentScript both when native imports
 // and the polyfill are in use.
-Object.defineProperty(wrappedDoc, '_currentScript', {
+Object.defineProperty(mainDoc, '_currentScript', {
   get: function() {
-    return HTMLImports.currentScript || wrappedDoc.currentScript;
+    return HTMLImports.currentScript || mainDoc.currentScript;
   },
   writeable: true,
   configurable: true
@@ -171,7 +172,7 @@ Object.defineProperty(wrappedDoc, '_currentScript', {
 // which may not be desireable; calls should resolve in the correct order,
 // however.
 function whenImportsReady(callback, doc) {
-  doc = doc || wrappedDoc;
+  doc = doc || mainDoc;
   // if document is loading, wait and try again
   var requiredState = HTMLImports.isIE ? 'complete' : 'interactive';
   var isReady = (doc.readyState === 'complete' ||

src/Parser.js

@@ -137,7 +137,7 @@ var importParser = {
     this.markParsingComplete(scriptElt);
   },
   nextToParse: function() {
-    return !this.parsingElement && this.nextToParseInDoc(document);
+    return !this.parsingElement && this.nextToParseInDoc(mainDoc);
   },
   nextToParseInDoc: function(doc, link) {
     var nodes = doc.querySelectorAll(this.parseSelectorsForNode(doc));

src/boot.js

@@ -32,7 +32,19 @@ HTMLImports.whenImportsReady(function() {
 });
 
 if (!HTMLImports.useNative) {
-  HTMLImports.observe(doc);
+  function bootstrap() {
+    HTMLImports.importer.bootDocument(doc);
+  }
+
+  // TODO(sorvell): SD polyfill does *not* generate mutations for nodes added
+  // by the parser. For this reason, we must wait until the dom exists to 
+  // bootstrap.
+  if (document.readyState === 'complete' ||
+      (document.readyState === 'interactive' && !window.attachEvent)) {
+    bootstrap();
+  } else {
+    document.addEventListener('DOMContentLoaded', bootstrap);
+  }
 }
 
 })();